Young Black men who have sex with men (YBMSM) ages 18 to 29 have been drastically affected by the HIV epidemic. Moreover, HIV+ YBMSM have lower rates of engagement in the HIV Care Cascade compared to other sub-populations, which includes the steps of being linked to care, retained in care, initiating and remaining adherent to antiretroviral therapy, and achieving viral suppression. HIV+ YBMSM living in the southern United States (the South) are a particularly at-risk group, as the South is the region in the U.S. with the highest HIV mortality. Despite the profound disparities in HIV morbidity and mortality affecting HIV+ YBMSM living in the South, there is a dearth of interventions to increase HIV+ YBMSM engagement along the HIV Care Cascade. Informal mentors who provide social support and role-modeling can help encourage health behaviors such as safer sex practices and increased self-advocacy in the healthcare system among adolescents and young adults, in general. Importantly, informal mentors are identified by many young MSM as positive influences in their lives. Thus, the inclusion of informal mentors already in the lives of HIV+ YBMSM in supporting HIV care engagement may be a promising strategy to reduce HIV disparities. Based on Social Action Theory (SAT) and Mentoring Theory, this exploratory R21 proposal seeks to examine the extent to which informal mentors can impact contextual (e.g., employment) and individual (e.g., self-confidence) factors predicted by SAT to be related to HIV care engagement among HIV+ YBMSM. Qualitative interviews will be used to explore ways informal mentors can impact factors important to the engagement of HIV+ YBMSM in HIV care. We will interview HIV+ YBMSM (n = 48), across both early and young adulthood and those engaged and not engaged in care, as well as HIV+ YBMSM reporting they do not have an informal mentor, to explore their perspectives regarding contextual and individual factors that affect HIV care engagement, and the extent to which informal mentors have helped address those factors. In addition, 24 dyads of HIV+ YBMSM and informal mentors (n = 48 people), representing a variety of types of reported factors affecting HIV care engagement, will discuss with each other ways that are acceptable to them both that mentors could help address particular factors that have affected the likelihood of each HIV+ YBMSM to engage in HIV care. Finally, based on the findings from the individual and dyadic interviews, the research team will outline content and format of an intervention involving informal mentors in supporting HIV+ YBMSM in engagement along the HIV Care Cascade. The team will elicit feedback on the intervention outline from a Community Advisory Board and Expert Panel throughout the intervention outline development process. This study will provide data vital to setting the stage for an R34 proposal to manualize and examine feasibility and acceptability of an HIV care engagement intervention that involves informal mentors for HIV+ YBMSM living in the South.